In many procedures, it is necessary to obtain access through bodily tissues. For example, in many cardiac procedures it is necessary to obtain access through the cardiac septum. Prior efforts to obtain access include piercing a small hole in the septal wall, typically at a location called the fossa ovalis (“FO”). Such access is term transseptal (“TS”) access.
TS access is often performed by delivering a sheath/dilator through the venous bed into the right atria and to the septal wall. With the tip of the dilator dragged along the septal wall, the same is dragged to the location of the FO. The sheath is then slightly advanced forward, applying pressure to the FO, creating what is called “tenting” of the FO. A long TS needle, e.g., a “Brockenbrough or “BB” needle, is then advanced through the lumen of the dilator that is inserted through the sheath. The needle is advanced against the FO while it is tented. The needle then punctures through the FO and into the left atrium.
The TS needle may be hollow or may incorporate a guide wire lumen to enable fluid delivery, and/or a guide wire or other minimally invasive tools to be threaded through and into the left atrium of the heart. Once the guide wire is passed through the TS needle into the left atrium, the needle, dilator, and sheath maybe retracted while the guide wire remains in the left atrium for subsequent procedures.
In about 20% of TS cases, there is difficulty obtaining TS access because of highly fibrosed tissue from previous TS procedures. Additionally, the TS sheath and the BB needle, as the same are being pushed forward by a physician, often slide up or down instead of the needle moving forward to penetrate the tissue, increasing the tension on the FO, causing the same to tent further adding additional stress to the target tissue, again while the needle attempts to penetrates the tissue. In other cases, if the septum is heavily fibrotic, significant pressure is required to advance the TS needle into the left atrium. Both cases occasionally cause puncture of the opposite wall of the left atrium by the sudden exertion of the needle through the septum and subsequent perforation, causing a severe adverse event and potential for death. To address this several currently marketed TS devices require Radio Frequency (RF) delivered to the needle to penetrate said target tissue in heavily fibrosed septums.